[chore][cmd/mdatagen] Align types for mdatagen configs

[jkoronaAtCisco]

Description

Replace JSON Schema vocabulary with Go-centric types in mdatagen config schema: int/bool/slice/map instead of integer/boolean/array/object, and merge items/additionalProperties into a single values field.

Testing

Unit tests and sample component aligned.

Documentation

1. Added list of supported types to README.md file
2. Metadata.yaml schema aligned

Authorship

• I, a human, wrote this pull request description myself.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.02%. Comparing base (52e6bf4) to head (d31ee19).

Files with missing lines	Patch %	Lines
internal/schemagen/schema.go	16.66%	4 Missing and 1 partial ⚠️
cmd/mdatagen/internal/cfggen/type_ref.go	71.42%	1 Missing and 1 partial ⚠️
cmd/mdatagen/internal/cfggen/docgen.go	87.50%	1 Missing ⚠️
cmd/mdatagen/internal/cfggen/generation.go	97.22%	1 Missing ⚠️
internal/schemagen/resolver.go	50.00%	0 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (85.71%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15659      +/-   ##
==========================================
- Coverage   91.03%   91.02%   -0.02%     
==========================================
  Files         729      729              
  Lines       48491    48463      -28     
==========================================
- Hits        44144    44113      -31     
- Misses       3020     3024       +4     
+ Partials     1327     1326       -1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[dmitryax]

LGTM with one nit

[dmitryax]

Let's move them all to enum constants. See the pattern we follow in the repo